Water-insensitive hydraulic fluids containing bis-borate esters or bridged-borate esters

ABSTRACT

This invention relates to water-insensitive hydraulic fluid compositions which contain at least one bis-borate or bridgedborate ester as the base component in said fluid composition. Such water-insensitive hydraulic fluids are high-boiling compositions particularly useful as brake fluids.

United States Patent Sawyer et a1.

WATER-INSENSITIVE HYDRAULIC FLUIDS CONTAINING BIS-BORATE ESTERS OR BRIDGED-BORATE ESTERS Inventors: Arthur W. Sawyer, l-lamden; David A.

Csejka, Orange, both of Conn.

Assignee: Olin Corporation Filed: Oct. 12, 1970 Appl. No.: 80,121

Related U.S. Application Data Continuation-impart of Ser. No. 717,997, Apr. 1, 1968, abandoned, which is a continuation-in-part of Ser. No. 653,335, July 14, 1967, abandoned.

U.S. Cl ..252 75, 252 496, 252/74, 252 77, 252/78, 260/462 R 1m. Cl. ..C09k 3/00 Field of Search ..252/78, 74, 75, 77, 49.6; 260 462 R 51 Jan. 18,1972

Primary Examiner-Leon D. Rosdol Assistant Examiner-Harris A. Pitlick Attorney-Eugene Zagarella, Jr., Gordon D. Byrkit, Donald F. Clements, F. A. lskander and Thomas P. Oday [57] ABSTRACT This invention relates to water-insensitive hydraulic fluid compositions which contain at least one bis-borate or bridgedborate ester as the base component in said fluid composition. Such water-insensitive hydraulic fluids are high-boiling compositions particularly useful as brake fluids.

14 Claims, No Drawings WATER-INSENSITIVE HYDRAULIC FLUIDS CONTAINING BIS-BORATE ESTERS OR BRIDGED- BORATE ESTERS This application is a continuation-in-part.of copending application Ser. No. 717,997 filed Apr. 1, 1968 and now 'abandoned, which in turn is a continuation-in-part of application Ser. No. 653,335 filed July 14, 1967 and now abandoned.

This invention relates to new and improved, water-insensitive hydraulic pressure transmission fluids for use in fluid pressure operating devices, such as hydraulic brake systems, hydraulic steering mechanisms, hydraulic transmissions, etc. More particularly, this invention relates to water-insensitive hydraulic fluids which employ as the base or lubricant one or more borate esters of glycol monoethers.

One of the basic objects of this invention is to provide hydraulic pressure transmission fluids for use in hydraulic systems which are extremely high boiling compositions and which maintain high boiling points even when water is added to the initial fluid composition. Another object of this invention is to provide a hydraulic pressure transmission fluid having a boiling point of at least about 374 F. A further object of this invention is to provide a hydraulic pressure transmission fluid having a high degree of lubricity while maintaining desired viscosities within a predetermined range under wide variation of temperature conditions.

A great number of hydraulic fluid compositions have been suggested in the art. Commonly, the hydraulic pressure transmission fluids, such as brake fluids are made up of three principal units. The first is a base or lubricant for the system which may include heavy-bodied fluids such as polyglycols, castor oil, mixtures of these materials, etc. Diluents, which are employed for the purpose of controlling the viscosity of the fluid as represented by glycol ethers, glycols, alcohols, etc., form the second basic unit. Finally, the third basic unit is represented by an inhibitor system comprising small quantities of inhibitors which are added to reduce oxidation, to improve wetting and flow and to maintain the pH of the hydraulic system above 7 in order to minimize corrosion. Although the hydraulic fluids of the prior art possesses one or more of the desired characteristics of viscosity temperature relationship, volatility, or pour point, they all suffer from one or more disadvantage and their use is handicapped by the fact that a wide range of suitable properties cannot be obtained. Fluids known in the art are not water-insensitive; they suffer from lack of lubricity; some are not stable against oxidation or deterioration, with others it is found that over long periods of use insoluble materials are formed which greatly reduce their effi' ciency; and in some instances exposure to oxidizing conditions also results in the formation of insoluble compositions. Frequently, it is found that these fluids are also corrosive and that they do not possess the required rubber-swelling properties.

It has been discovered that the hydraulic fluids of this invention which contain as the main base or lubricant at least one bis-borate ester or bridged-borate ester are of low cost; they possess a high boiling point and are essentially odorless and colorless; they possess a high degree of compatibility with other fluids; they exhibit a very low rate of corrosivity; and, especially desirable, they have a high degree of water tolerance.

Another feature of this invention is the highly satisfactory rubber compatibility of the novel fluids as shown in tests carried out according to SAE Standard J70c. Fluids previously employed having utilized expensive materials such as 2ethylhexanol, heptanols, butyl ethers of glycols, or diethers of glycols in an amount from about 10 to about 30 percent by weight of the total composition to achieve the desired rubberfluids of this invention are derived from the lubricant or base portion. The importance of the rubber-swelling properties of the fluid cannot be overlooked since too little swelling will result in leakage of the fluid past the rubber cup sealing means and past the piston in hydraulic cylinders with corresponding loss of power. On the other hand fluids which cause too much rubber swelling are not desirable in that they destroy the structural properties of the rubber sealing cups in hydraulic cylinders, which in turn, results in malfunction or inoperativeness of the unit.

A great deal of public interest has been generated in the safety qualities of hydraulic brake fluids as is pointed out, for example, by C. F. Pickett in an article entitled Automotive Hydraulic Brake Fluids" which was published as a part of the 51st Mid-Year Meeting Proceedings of the Chemical Specialties Manufacturing Association, Inc., 50 East 41 Street, New York, NY. 10017 (1965). The efiect of water on hydraulic brake fluids has been studied extensively and it is now recognized and agreed that the presence of water has a dramatic effeet. on lowering of the boiling point. A high boiling point of the brake fluid is necessary to prevent vapor lock which results in a loss of braking power thus frequently causing an accident. As pointed out in the above-mentioned article, when 4 percent water was added to three different commercial brake fluid compositions having boiling points of 558 F. (A), 518 F. (B), and 470 F. (C), the resulting fluid compositions exhibited boiling points of 271 F., 274 F. and 275 F., respectively. Thus fluid A had dropped 287 F. in boiling point, fluid B, 244 F., and fluid C, 195 F. In contrast, a hydraulic brake fluid composition of this invention having a boiling point of 505 F. on addition of 4 percent water registered a drop in boiling point of only 138 F. and the same fluid with 7 percent added water had a boiling point drop of 188 F. A second hydraulic fluid composition of this invention having a boiling point of 47 1 F. exhibited a boiling point drop of F. on addition of 4 percent water. Thus, it is apparent that the hydraulic brake fluids of this invention are distinctly superior to those of the art.

LUBRICANT OR BASE COMPOSITIONS The lubricant or base compositions employed in the novel hydraulic fluids of this invention comprise at least one bisborate ester or bridged-borate ester as the main base or lubricant and, optionally, may contain a minor amount of a polyoxyalkylene glycol having a molecular weight of not less than 150. Generally the amount of borate ester used in the fluid may vary widely. More particularly, the borate ester used in the hydraulic fluid will comprise from about 20 to about 92 percent by weight and preferably from about 44 to about 92 percent by weight, the percent by weight being based on the total fluid weight.

The amount of polyoxyalkylene glycol used may generally comprise from 0 to about 20 percent and preferably from 0 to about 16 percent by weight of the total fluid composition.

A wide range of polyoxyethylene glycols can be employed in the base or lubricant compositions of this invention. Useful polyoxyalkylene glycols include those having molecular weights ranging from not less than about to about 400, and preferably from about 200 to about 350. Suitable polyoxyalkylene glycols include polyethylene, polypropylene and polybutylene glycols with polyethylene glycol being particularly preferred.

Although a wide variety of bis-borate esters or bridgedborate esters can be employed as the base in the novel hydraulic fluids of this invention, an especially useful class of borate esters are the so-called bis-borate esters of glycol monoethers swelling characteristics. The rubber-swelling properties of the 70 having the general formula:

wherein R, and R are independently selected from the group consisting of hydrogen and methyl; R R R and R are each an independently selected alkyl group having from one to four carbon atoms and n and m are positive integers independently selected in each chain and whose sum in each chain is from 2 to 20.

Borates of the above-mentioned type (1) can be conveniently prepared by reacting orthoboric acid and a glycol monoether or a mixture of glycol monoethers while in the presence of a water-azeotrope-forming solvent. Water formed in the esterification reaction is continuously removed as the azeotrope. At first, the temperature of the reaction mixture is maintained between about 0 C. and about 200 C. and desirably at the distillation temperature of the water-solvent azeotrope. After essentially complete removal of the water formed during the esterification (i.e., 2.5 moles when 2 moles of glycol monoether are reacted with each mole of orthoboric acid), the reaction temperature will rise to the boiling point of the solvent at which time the excess solvent is conveniently removed from the reaction mixture by distillation. The bisborate ester product, which is left as the residue, may then be recovered by stripping under reduced pressure or by extraction with a suitable solvent followed by evaporation of the solvent. For example, the compound:

can be prepared by reacting 3 moles of CH (OCH Cl-l Ol-l, 1.50 moles of orthoboric acid and 380 ml. of toluene with heating and mixing to yield 51 1 grams of the ester, a clear, yel low liquid boiling at 602 F. (as determined by ASTM Method D-l 120-65). The preparation of bis-borate esters of this type is more completely described in the Sawyer and Csejka application for Bis-Borates Prepared From Glycol Monoethers and Boric Acid, application Ser. No. 653,339 filed on July 14, 1967, and now abandoned and which in its entirety is incorporated herein by reference.

A second highly useful class of borate esters include bridged-borates of the general formula:

where R and R are independently selected from the group consisting of hydrogen or methyl; R and R are each an independently selected alkyl group having from one to four carbon atoms; R is the organic residue exclusive of reactive hydroxyl groups ofa polyol, p is an integer offrom 2 to 6 inclusive and n and m are positive integers independently selected in each chain and whose sum in each chain is from 2 to 20.

In general, the Type II bridged-borates are prepared in two steps. In the first step, a stoichiometric amount of a boroncontaining compound, such as orthoboric acid, is reacted with a glycol monoether or mixture of glycol monoethers to yield an intermediate borate compound which is reacted with a polyol having from 2 to 6 inclusive hydroxyl groups to obtain the Type 1] bridged-borate compounds. The two reactions, namely the reaction of the first stage and the reaction of the second stage, proceed as shown in the following equations where, for purposes of illustration, a single glycol monoether is utilized in preparing compound A:

v B-0H em wherein R R R,,, n, m and p have the same meaning as previously described and R is alkyl of from one to four carbon atoms.

In the preferred method of preparation, boric acid is employed as the boron-containing material and an inert waterazeotroping solvent is added to the reaction vessel along with the glycol monoether starting material. The water-azeotroping solvent is selected so that the azeotrope distills at a temperature below the boiling point of the monohydroxy compound.

. The temperature of the reaction mixture is initially maintained preferably between 0 and 200 C. and desirably at the distillation temperature of the water-solvent azeotrope. The use of a graduated Barrett receiver facilitates the measurement and separation of the water of condensation. Preferably, the reaction is conducted without an added catalyst to simplify the utilization of the product, although an esterification catalyst may be employed, if desired. When the water removed is equivalent to the stoichiometric requirement to yield the intermediate borate compound (A), the reaction mixture is cooled to a temperature below its reflux temperature and a stoichiometric amount of a polyol bridging" compound is introduced into the reaction mixture. After stirring the mixture to ensure uniformity, it is again heated so that azeotropic removal of water is resumed. As soon as the removal of water is essentially completed, the solvent is then conveniently removed by distillation. The borate ester remaining after removal of the solvent can be further distilled under reduced pressure to remove any unreacted starting materials present. Other methods are known in the art for purifying the borate ester. For example, the ester can be recovered as the pure product by extraction with a suitable solvent followed by evaporation of the solvent.

The preparation of a bridged-borate ester useful in the hydraulic fluids of this application is illustrated below.

A total of 985 g. (6 moles) of CH (OCl-l Cl-l OH, 185.5 g. (3 moles) of orthoboric acid and 510 ml. of toluene were mixed together in a 2-liter, round-bottom, 3-neck flask equipped with a magnetic stirrer. With heating at reflux temperature and stirring, the water of condensation was removed as formed by azeotropic action. When 108 ml. (6 moles) of water had separated, the reaction mixture was allowed to cool below reflux temperature. Then 179 g. (1.5 moles) of 2- methyl-2,4-pentanediol was introduced and the reaction mixture was stirred and reheated to reflux temperature in order to resume azeotroping out the water of condensation. As soon as the water had been essentially all removed, the toluene was distilled off and the residue containing the product was stripped under water aspirator vacuum at to 120 C. pot temperature for 1.5 hours-in order to remove unreacted products. A total of 1,192 g. of product (essentially percent of theory), a clear colorless liquid with a viscosity at 40 C. of approximately 1,400 cs. and having the formula:

. iii."

cmwcmcnmo 0(CH=CH: )a H:

was obtained. The preparation of other Type 11 bridgedborates is described in detail in the Sawyer and Csejka application for Borate Esters Prepared by Successive Reactions of Boric Acid with Glycol Monoethers and Polyols, application Ser. No. 653,337 filed on July 14, 1967, and which in its entirety is incorporated herein by reference.

If desired, mixtures of the bis-borate esters and the bridgedborate esters can be utilized in formulating the novel hydraulic fluids of this invention.

DILUENTS The amount of the diluent portion of the novel fluid composition of this invention may vary widely and more particularly may comprise from about 3 to about 50 percent by weight based on the total weight of the fluid composition of one or more diluents which are glycol monoethers or diethers of the formula:

wherein R is alkyl from one to four carbon atoms, R is selected from the group consisting of hydrogen and alkyl of from one to four carbon atoms, 1: is an integer from 2 to 4, and y is an integer from 2 to 4. Preferably, the hydraulic fluid composition will contain from about 6.5 to about 48 percent by weight, based on the total weight of the fluid composition, of the glycol monoether or diether. Useful glycol monoethers and diethers, many of which are commercially available include, for example, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol mono-nbutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol mono-n-butyl ether, tetrapropylene glycol monomethyl ether, dibutylene glycol monomethyl ether, tributylene glycol mono-n-propyl ether, tetrabutylene glycol mono-n-butyl ether and the corresponding diethers thereof.

ADDITIVES When desired, inhibitors for pH and corrosion control, such as alkaline inhibitors as exemplified by the alkali metal borates, can be employed in an amount sufficient to maintain alkaline conditions in the fluid compositions, e.g., a pH value of from about 7.0 to about 1 1.5. These inhibitors are generally added in an amount of from about 0.5 to about 6.0 percent by weight based on the total weight of the fluid composition and preferably from about 0.8 to about 5.0 percent by weight on the same basis. Useful inhibitors include alkali metal borates, such as sodium borate, potassium tetraborate, etc., sodium meta arsenite; alkali metal salts of fatty acids, such as potassium oleate', the potassium soap of rosin or tall oil; alkylene glycol condensates with alkali metal borates, such as the ethylene glycol condensate of potassium tetraborate; amines, for example, ethanolamine, methyl diethanolamine, diethanolamine, di(2-ethylhexyl) amine, di-N-buty] amine, monoamyl amine, diamylamine, dioctylamine, salicylal monoethanolamine, di-B-naphthyl-p-phenylene diaminc, N ,N'-disalicylidene-1,2-propanediamine, N,N'-disalicylal ethylene diamine, dicyclohexylamine, and amine salts such as mono or dibutyl ammonium borate; phosphites, such as triphenyl phosphite, tri(tert. amylphenyl) phosphite, diisopropyl phosphite, etc., mercaptobenzotriazole; morpholine compounds including alkyl morpholines having from one to four carbon atoms in the alkyl group such as N- ethyl morpholine, N-isopropyl morpholine, N-butyl morpholine; N-phenyl morpholine, N-(2-aminoethyl) morpholine, N-(Z-hydroxyethyl) morpholine, etc.,

phosphates, including the alkali metal phosphates, dibutyl amine phosphates, the dialkyl acid o-phosphates and amine salts thereof; triazoles including benzotriazole, 1,2- naphthotriazole, 4-nitrobenzotriazole, aminobenzotriazoles, such as S-acylamino benzotriazole, and alkyl triazoles having one to 10 carbon atoms in the alkyl group as exemplified by methyl triazole, ethyl triazole, n-propyl triazole, tertiary butyl triazole, hexyl triazole, isodecyl triazole, etc. Other useful corrosion inhibitors include adenine, 4-methylimidazole, 3,5- dimethyl pyrazole, 6-nitroidazole, imidazole, benzimidazole, guanine, indazole, ammonium dinonylnaphthaline sulfonate, dioleyl thiodipropionate, ethylbenzoate, ethyl-paminobenzoate, cyclohexyl ammonium nitrite, diisopropyl ammonium nitrite, butynediol, l,3,5-trimethyl-2,4,6-tris (3,5- di-tert. butyl-4-hydroxybenzoyl), 4,4"methylene bis(2,6-ditert. butylphenol), 4-hydroxymethyl-2,6-di-tert. butylphenol, 4,4-methylene bis(4-methyl-6-tert. butylphenol), salicylal-oaminophenol, 2,6-di-tert. butyl-Z-dimethylamino-p-cresol, 4,4 -thio bis(6-tert. butyl-o-cresol). Mixtures of the abovementioned inhibitors can be employed if desired.

Preferably, the hydraulic fluid compositions of this invention contain from about 0.001 to about 1.0 percent by weight of an antioxidant based on the total weight of the fluid composition, to protect the diluents. Typical antioxidants include phenolic compounds, such as 2,2-di-(4-hydroxyphenyl) propane, phenothiazine, phenothiazine carboxylic acid esters, N-alkyl or N-arylphenothiazines, such as N-ethyl phenothiazine, N-phenyl phenothiazine, etc.; polymerized trimethyldihydroquinoline; amines, such as phenyl-anaphthylamine, phenyl-fi-naphthylamine, N,N'-dioctyl diphenylamine, N,N-di-B-naphthyl-p-phenylene diamine, pisopropoxy diphenylamine, N,N-dibutyl-p-phenylene diamine, diphenyl-p-phenylene diamine, N,N'-bis( 1 ,4-dimethylpentyl p-phenylene diamine, N,N-diisopropyl-p-phenylene diamine, p-hydroxydiphenylarnine, etc.; hindered phenols such as dibutyl cresol, 2,6-dimethyl-p-cresol, butylated 2,2-di-(4-hydroxyphenol) propane, n-butylated aminophenol, butylated hydroxyanisoles, such as 2,6-dibutyl-p-hydroxyanisole; anthraquinone, dihydroxyanthraquinone, hydroquinone, 2,5- ditertiary butylhydroquinone, 2-tertiary butylhydroquinone, quinoline, p-hydroxydiphenylamine, phenyl benzoate, 2,6- dimethyl p-cresol, p-hydroxyanisole, nordihydroguaiaretic acid, pyrocatechol, styrenated phenol, polyalkyl polyphenols, sodium nitrite, etc. Mixtures of the above-mentioned antioxidants can be employed, if desired. It should be emphasized that with a variety of the fluids of this invention, which are suitable for a wide range of industrial application, a separate antioxidant is not required.

Other well-known'additives, utilized in hydraulic fluids for various purposes, may also be incorporated into the fluids of this invention if desired. Several additives useful in hydraulic fluids are disclosed in Introduction to Hydraulic Fluids" by Roger E. Hatton, Reinhold Publishing Corporation, 1962.

Formulation of the novel of this invention is accomplished by blending the components to a homogeneous stage in a mixing vessel. The preferable blending temperature is from about 50l25 F. It is preferable to warm the solution during preparation to facilitate dissolution. The blending of the compounds is conveniently conducted at atmospheric pressure in the absence of moisture.

In general, any suitable method can be used in preparing the liquid compositions of this invention. The components can be added together or one at a time, in any desired sequence. It is preferable, however, to add the antioxidant and alkaline inhibitor as a solution in the glycol ether component. All components are mixed until a single phase composition is obtained.

The following examples which illustrate various embodiments of this invention are to be considered not limitative.

Diethanolamine Polyethylene glycol (molecular weight 300) Phenotbiazlne Sodium nltrite The following physical properties indicate the utility of the above composition as a hydraulic fluid:

1. Boiling Point 454 F., determined by ASTM Method D- 2. Viscosity at 40 F., 1,745 centistokes, determined by ASTM Method D-445-64. When held at 40 F. for 16 days, the formulation remained a clear uniform liquid. Immersion of iron, steel, aluminum and copper metal coupons in this formulation for days at 212 F. did not cause corrosion as evidenced by lack of pitting or etching.

Natural rubber and styrene-butadiene rubber sealing compounds were not degraded by immersion in this fluid formulation for 5 days at 158 F.; their size, shape and hardness remained in usable condition.

The reflux boiling point of this formulation is reduced from 454 F. to 350 F. by addition of 3.5 percent by volume of water and after refluxing for 10 minutes, whereas a commercial hydraulic brake fluid with a reflux boiling point of 463 F. exhibited a reflux boiling point of 290 F. on addition of 3.5 percent by volume of water and after refluxing for 10 minutes.

U.S. Public Law 87-637 requires that hydraulic brake fluids in commerce must have a boiling point minimum of 302 F.,

EXAMPLE III The above hydraulic fluid was found, by test methods of SAE Standard J70c, to have a boiling point above 500 F a viscosity at 40 F. of less than 1,800 cs. and a flash point above 300 F. These properties indicate usefulness as a hydraulic fluid over a wide temperature range.

this level being interpreted as a minimum safety level for operation of motor vehicles on the highway. EXAMPLE IV In this example and in all other examples of this specifica- Percent tion, the reflux boiling point was determined according to the g procedure of ASTM 1 120-65 which is the reflux boiling point procedure referenced in SAE Standard .1700. 2 2)a 2 2 )3 3 BO-B CH (OOH,CH:) O O(OH,CH;O) CH;

EXAMPLE II Triethylene glycol monornethyl ether 23. 70 3O Polyethylene glycol (molecular weight 300). 10. 00 Percent Tetraethylene pentamine 1. 00 by Phenothiezlne 0. 29 Weight Sodium nitrite 0. 01 CH; (OCHgCH2)3O 74 95 Total 100.

8-0 f f h b r The exceptional properties 0 the fluid o t e a ove ormu- OH OCH CH O z CH3: 01143 lation are illustrated by its high reflux boiling point which was CH;(0CH1 H2)a0\ CH; 51 1 F.; by its low-temperature fluidity, as shown by the B o viscosity at 40 F., which was 4,227 es. and by its low pour oint as shown when a clear liquid resulted after 6 hours in the CH 40 P. V

OCHZCHMO temperature range of 5 8 to 78 F. 'Iriethylene glycol monornethyl ether 7. 50 Diethanolamino 2. 00 Polyethylene glycol (molecular weight 200). 15.00 EXAMPLE V Diphenylol propane 0. 50 Sodium nitr te- 105 Perc glt V Total 100.0 Weight 7 CH (OCHgCHz) O\ /0(CH2OH20)3CH3 45.85

/B--OB\ This formulation .when tested in accordance with the ap- CH3(OCH1CH2)IO 0(CH2CH20)3CH1 propriate methods of the Society of Automotive Engineers Polyethylene glycol (molecular weight 300 4. 0g

Triethylene glycol monomethyl ether 47. 4 Standard J70c for Hydraulic Brake Fluids exhibited the fol Methyl diemanolamme bomte u 2.50 lowing properties: Sodium nitrite 0.02 Dioctyl diphenylamine 0. 10 Phenothiezine 0. 05 Butylated dlphenylol propane 0. 05 Reflux Boiling Point 509" F- Total I00. 00 Viscosity at 2l2 F. 2.7 cps.

at -4o= F. 3,380 cps. Cnld 6 y at a clear i i This composition has the functional properties of a hydrau- Rubber Swcmn 6 58 60 he fluid as evidenced by wide liquid-temperature range, com- (Nam? Rubbcn 120 how patibility with rubber seals, water tolerance and approximateiszi F.) 2.5 percent ly neutral or slightly alkaline pH to minimize corrosivity. The ig yf- 4 2 following properties were determined by applicable methods v percent Wm Tolmnc: (l5 pmcm by VQL added Wm") of Society of Automotive Engineers Standard J 70c.

24 hours at 40 F. clear liquid 24 hours at I40" F. clear liquid Reflux Boiling Point 468 F. Viscosity at 2l2 F. 2.5 cps.

at 40 F. 1,550 cps. Rubber Swelling The above properties demonstrate the outstanding proper- (Natural Rubber, 5 days, ties of this formulation as a hydraulic fluid. The addition of 3.5 'g P percent by volume of water to the formulation yields a comf t fzf' i'gi gj 3 3 We! position having a reflux boiling point of 368 F whereas typiwin ol c cal currently commercial brake fluids with 3.5 percent added F lia flddcd q Water) at F. clear liquid water have inferior (below 302 F.) reflux boiling points in the Cold Ten (6 days a! F) Clear quid range of 240 to 290 F.

Polyethylene glycol (molecular-weight150). w 2.50 'll'lcthylcnc glycol monomcthyl other. 23. l)icthanolarnlnc 1.00 lhcnothlazlne 0.14 N,N- dioctyl dlphenylaminc 0. 14 Sodium nitrite v l 0.02

Total 100. 00

The desirable properties of this fluid, as determined by test were measured according to the methods of SAE Standard methods in SAE Standard J 700, were approximately as fol- 20 17 lows:

Reflux Boiling Point 50l F. g-m, Boiling point F Boiling Point with 3.5 percent vol. added water 375 F. viscosity at e F. 1,700 cps Viscosity at 40 L790 cps. PH Rubber Swelling Styrene-Butadiene. 70 hours at 248 25 F. L9 percent EXAMPLE VII Percent by weight GH (OCH2CH2)30 ()(CHzCHzO)aCHa 70.0

BO OB OH (O CHzCHmQ CH -CCHz-(|J-CH= 0 (CH2CH2())3CH3 OH: H

'Iriethylene glycol monomethyl ether 15. 8 Polyethylene glycol (molecular weight 300) 12. 0 -hydrox yethyl rnorpholine 2. 0 Butylated dlphenylol propane 0.2

Total 100. 0

The above formulation was tested according to the Water Tolerance (3.5 percent by vol. of added water) procedure of SAE Standard J70c and the following properties f z "q were observed:

EXAMPLE IX Reflux Boiling Point 538 F. Boiling Point with 3.5 percent vol. added water 387' F. Pal-cast Viscosity at -40 F. 1,954 cps. 181% Rubber Swelling-StyreneButadiene 70 hours at 248 1.9 percent 011,, 0 omcnmo 0 Water Tolerance (3.5 percent by vol. of added water) at 40 C. clear liquid. B-O-CH2 CH (O CHzCH2)aO L I EXAMP E VI I a 2 2 a P co t B0 H weight CHKOCHzCHzhO 54. 50 2 Ht)a OH (OCH2CH2) O BOCH2 2 CII3(OCH2CH1)3O CH3(OCH2CH2)a0 C H3 (0 0 H2O H2) Triethylene glycol monomethyl ether 39. 8 H Polyethylene glycol (molecular weight 300) 3- 0 N-hydroxyethyl morphollne 2. 0 0 Ha 0 05 0 H2) 3() Phenothlazine 0. 2 011 0 0112011930 TotaL 100-0 BO- H2 I M T O The outstanding charactenstlcs of this hydraulic fluid are 11- 011400112 IIzhO lustrated by the following properties which were determined Triethyleno glycol monomethyl other 0- 0 according to the procedure of SAE Standard J c. Polyethylene glycol (molecular weight 300) 3. 00 1) lethanolami nc 2. 25 Phenothiazlne 23 7 Reflux Boiling Point 505 F. Sodium mtrite Viscosity at 40 F. |,950 cps.

Boiling point with 3.5 percent vol. added water 376 F. Total u 00 Water Tolerance (3.5 percent by vol. of added water) A r e at 40 F- clear liquid Rubber Swelling Styrene-Butadiene, 70 hours at 248 F. 2.1 percent pH 7.0

The outstanding characteristics of this fluid formulation as a hydraulic fluid are shown in the following properties which EXAMPLE X Percent by weight C 11 0 H2O H2)i0 O}C HgCH20 3CH3 75. 0

B-OCH2C(CH3)2CHzO-B CH3(OCH:CH2)3O O CHzCHzOhGH;

Tricthylenc glycol monomethyl ether 13. 2 Polyethylene glycol (molecular weight 300) 10. 0 Methyl diethanolamlne 1. 5 Butylatcd diphcnylol propane 0. 3

The hydraulic fluid of this example was tested according to EXAMPLE XII the procedure of SAE Standard J 70c and the following values Percent were observed: y weight Reflux Boiling Point 532 F. Viscosity at 40 F. 2.l28 cps. CH3(OCHZCHZ)!O 0}CHzCI-Ig0); 0 H; 52. 0 Rubber Swelling Styrene-Butadiene 3 days at 248 F. 3.9 percent 13-0-13 Water Tolerance (3.5 percent by vol. of added water) at 40 F. clear liquid CH3(OCH2C Q50 C(CHzCHzQhCHg s a Pol"! Wllh P y of added Water 3 0 Triethylene glycol monomethyl ether 40' 3 p N,N'-dioctyl diphenylarnine.-. 0.2 Polyethylene glycol (molecular weight 300). 6. 0 EX MPLE XI N -hydroxyethyl morpholine l. 6

Percent TOttil 100. 0

by weight CHAOCHZCHMO 0 When the above hydraulic fluid was tested according to the appropriate procedures of SAE Standard J 70c, It exhibited the 0 following properties: CH (0CH2CH2)4O CHKQCHZCHMQ Reflux Boiling Point 480 F.

Viscosity at 40 F. L755 cps. BOCH2CCHz-CH;

XAMPLE XIII oH, 0cHI0HI)Io E ercent CH5(0CH2CH2)3O B y 0 H2 weight 0 0 C O 0 C CH 50. 00 CEMOCHQCHQBO Ha( CH2 Hi); )CH: H20); 3

3 Trlethylene glycol monomethyl ether 38. 6 g o B Polyethylene glycol (molecular weigh 3. 0 011;,(0 0 H10 0 0 (CH C H OhOH; Diethanolamine 1. 2 Phenothiazine 0 2 gollyttghlylenelglyclol mole i ui ir ei m 20o) 2% re yenegyeo monoe y e er Total 0 Diethanolamine 1. a0 N,N dioetyl diphenylarnine 0. 18 Sodium nitrite 0. 02 The hydraulic fluid of this example was tested according to T ml 100 00 the procedure of SAE Standard J 700 and the following pro- 0 EXAMPLE XIV Percent by weight CH (OCH,CH;) O\ /O(CH:CH1O)3CH3 68.0

B-0 0-B CH (OCH2CH1) O 0(CH2CH10)3OH3 CH;- CH2 H-OH;

Polyethylene glycol (molecular weight 300) 10.0 'Iriethylene glycol monomethyl ether 10.0 Triethylene glycol monobutyl ether. 10.0 Hydroxyethyl hydrazine 2. 0

Total. 100. 0

perlies were obsefvedi The above hydraulic fluid composition was tested according to the appropriate procedures of SAE Standard J70c and the following results were obtained:

Reflux Boiling Point 5l7 F. o viscosity m Mm: F "656 CPL Reflux Boiling Point 495 F.

(old Test (6 days at 40 F.) clear liquid vi'comy .40. F' 3.029 cps Boiling Point with 3.5 percent vol. of added water 388' F. pH 7.9

. .13 .ll; EX I IIE xv Percent by weight CH3(OCH2CHB)IO I (CH1C3a0hCHa 65.0

3-0 0-13 CH (OCH2CH2) O C(CHzQHiQhCHa CHg- -CH:- H-OH;

Triethylene glycol monoethyl ether 2a. 5 Polyethylene glycol (molecular weight 200)- 10. 0 Dlethanolamine 1. 5

Total 100. 0

The above is an example of a hydraulic fluid which is highly EXAMPLE XVIII water-insensitive and which employs a polyethylene glycol of I Percent molecular weight 200. by weight OwmGH OhGHI 5o. 0

cH 0B EXAMPLE XVI o f O/(CHIQHIO)IGHS HG O-B Percent CHAOCHQGHQBO QCHQCHgOhCl-I;

by 1 cmmcmonmo 50 o crmoomcg o (1 0 H,cH,o IcH,

B-O-CH-z HOD-13 CH; (0 cHIcHoIo chcmofiwollcm cHawcmcHmo 3S, owmcmohcn,

B-O-CHr- -cHI-oHI cmwcHIoHIm zc h cH wcHIcHIm owfl'lcniohcnfl B-O- Hg 40 0 H O-B CHKOCHCHzhO O(CHQCH QO)BGHS 'Irlethylene glycol monomethyl ether 88, 6 Trlethylene glycol monomethyl ether 40. 6 Polyethylene glycol (molecular weight 200). 10, 0 Dlethanolemlne; 1, 2 Dlethanolamine 1.2-. Phenothlazine 0. 2 Phenothiazine 0.2 I Polyethylene glycol (molecular weight 3 8. 0

EXAMPLE XV II- EXAMPLE XIX EXAMPLE XXII Percent Percent by y weight weight CH;( CH,C{I\2):.50 0}CH,CH,O) CH; 70.0 5 O(CH1CH G);CH; 62. 00

13-0 0--B\ CHgO-B 2):.5 0 )a.s l O(CHaCH|O);CHa

CH; CH -CHCH; O(CH;CH O)ICH;

HOB

Trlethylene glycol monomethyl ether 23.0 0(CHzCH10);CH; N-hydrox yethyl morphollne 2. 0 Polyethylene glycol, 300 molecular weight. 5. 0 0 (CI'hCHgOhCH:

Total 100 0 l s HgO-B 0(CH2CH10);CH;

Trlethylene lycol monomethyl ether 43. 00 Dlethanolam no 1.70 Polyethylene ycol molecular weight 300).. 3. 00 Butyleted dip enylo propane 0. 28 Sodium nltrlte 0. 02

Total 100. 00

EXAMPLE XX Percent Y weight CH3 0CH2CH2)3O ($0 HgCHzOhCH; 68.00

B-O 0--B CH;,(OCH2CH2)3O 0(CH20Hz0) CH;

CH CH2CHCH;

Triethylene glycol monomethyl ether 18. 20 Diethanolarnine. 1. 28 Polyethylene glycol (molecular weight 300) 12.00 Dlphenyiol propane 0.50 Sodium nitrite 0. 02

Total 100. 00

EXAMPLE XXIII Percent r by welght CH;(OCH,CH,),O 0)OH,CH,0)CH; 68.00

B0CH,C (OHe)2CH:0-B ongocmclnno owmcmomm Triethylene glycol monomethyl ether 18. Polyethylene glycol (molecular weight 300). 12. 00 Diethanolamlne 1. 28 Butylated dlphenylol propane. 0. 30 Sodium nitrite 0. 02

Total 100.

EXAMfl-E- XXL! Percent y weight EXAMPLE XXI CHI(OCHQCH})3O O/(CHgCHgOhCH: 40.00

Percent 0 B\ omwcmcmno owmcmo cm Trlethylene glycol monomethyl ether 48. 00 (CH2CH20)aCHa 44. 00 Diethanolamme L n B Polyethylene glycol (molecular weight 300). 10.00 7Q Phenothlezlne 0. 05 ClMOCIhCHmO own omo cn, sd1um 'lrlethylvnc glycol monomcthyl other 44, 00 Total 00 Dictlnmolumine l l. 90 gglyctiiyilcne glycol (molecular weight 200). 10.00 8058331355333:1:1111:::11;1111;1:;:;:1;1 3332 75 The above formula ion had a reflux boiling oim of439 F. Tom and after the addition of 3.5 percent by volume of water to the formulation hard a refluxloiling polntof 333 EXAMPLE XXV and (C) from about 3 to about 50 percent by weight-based on Percent the total weight of the fluid of at least one diluent having the by formula: weight mo cu 1 R cmwcmomho oyzmomohom 30.00 2

. wherein R is alkyl of from one to four inclusive carbon atoms,

B OB\ R is selected from the group consisting of hydrogen and alkyl M HiC IzM 0(GH2CH20)8CH3 of from one to four inclusive carbon atoms, x is an integer of Triethylene glycolmonomethyl ether 0 58m from 2 to 4 inclusive and y is an integer of from 2 to 4 inclu- Diethanolamine 1. 90 sive.

iggfgg g 'ig (mflecular weight 3% l0 2. The hydraulic fluid composition of claim 1 wherein said Sodium nitrite: IIIIIII:I:I:IIIII:II -IIIIIII 0:05 composition additionally includes from about 0.5 to ab0ut 6.0 Total 1mm percent by weight based on the total weight of thefluid toan inhibitor for pH and corrosion control. a 3. The hydraulic fluid composition of claim 2 wherein said The above formulation had a reflux ng Point 0 F- composition additionally includes from about 0.001 to about and after the addition of 3.5 percent by volume of water to the 1.0 percent by weight of an antioxidant. formulation had a reflux boiling P of 32 4. The hydraulic fluid composition of claim 3 wherein the said base or lubricant is: EXAMPLE XXVI 5. The hydraulic fluid of claim 3 wherein the said base or CH (0CH10H2);0 0(CH2CHaOhCH: lubricant is:

1 68.00 ii fiiiififliin ififffifffffflififffiiiiii: 1.90 ifih ihiilifi ifi .ffiiiiff?TF1??? 3: 5 Swim cmwcmcmno 0H.- oH,- H-OH; 0 0H,0H,0 ,0H, Total 100.00 (I:

The above formulation had a reflux boiling point of 438 F. 5 The hydraulic fluid f claim 3 wherein h id b or and after the addition of 3.5 percent by volume of water to the l b i i formulation had a reflux boiling point of3 14 F. What is claimed is: 1 K L M I 2 l. A hydraulic fluid composition consisting essentially of B z a)i r (A) from about 20 to about 92 percent by weight, based on cmwcmcmho ()(CHCHOhCH; the total weight of the fluid composition, of at least one base 40 or lubricant selected from the group consisting of (a) a borate 7. The hydraulic fluid of claim 3 wherein the said base or ester of the formula: lubricant is:

Rs[(0CHzCHR -(OCHzCHR2)n0] [O (RzCHCHgOh-(RqCHCH20) ]R5 /BO--B\ EH9 H Q B MTKQ PEZQE BZZ L [0 (RicHCHio) CHCHZOM wherein R and R are inde end ntl lected f th 0 I 1 2 p e y se rom e gr up CHKOGHCHMO consisting of hydrogen and methyl; R R R, and R are each an independently selected alkyl group having from one to four BO-CH carbon atoms and n and m are positive integers independently 0Hs( i a)a selected in each chain and whose sum in each chain is from 2 OH OCH CH O to 20; and (b) a borate ester of the formula: K a I):

BO H R [(OCH2CHR )m(0 cmcmmno I w z m OH;(OCH,CHg)aO ,.,BL 92E29 J BO OHAOCH CHQsO where R, and R are independently selected from the group b.

consisting of hydrogen or methyl; R and R are each an independently selected alkyl group having from one to four carbon 6 8. The hydraulic fluid of claim 3 wherein the same base of atoms; R is the organic residue exclusive of reactive hydroxyl lubricant is: 7 V groups of a polyol, p is an integer of from 2 to 6 inclusive and n y and m are positive integers independently selected in each a( i0 i):.s0 a ):.s r chain and whose sum in each chain is from 2 to 20; (B) from 0 0-B to about 20 percent by weight based on the total weight of the fluid composition of a polyoxyalkylene glycol having a CHKOCHCHMOV GH' L H CH3 ()(cH'cfiama'ncm molecular weight of not less than 150 and up to about 400 0H3 mkoaluminum-(omcunmo] 9. The hydraulic fluid composition of claim 3 wherein the said polyoxyalkylene glycol is a polyethylene glycol having a molecular weight of 300.

10. The hydraulic fluid composition of claim 3 wherein the said diluent is triethylene glycol monomethyl ether.

11. The hydraulic fluid composition of claim 3 wherein the said antioxidant is a mixture of sodium nitrite and phenothiazine.

12. The hydraulic fluid composition of claim 3 wherein the said inhibitor is diethanolamine.

13. The hydraulic fluid of claim 1 wherein the base or lubricant portion is from about 44 to about 92 percent by weight based on the total weight of the fluid composition.

14. In the operation of a fluid pressure operating device which uses hydraulic pressure transmission fluid, the improvement comprising using as the base component in said hydraulic pressure transmission fluid at least one borate ester selected from the group consisting of (a) a borate ester of the formula:

wherein R, and R, are independently selected from the group consisting of hydrogen and methyl; R,, R R and R are each an independently selected alkyl group having from one to four carbon atoms and n and m are positive integers independently selected in each chain and whose sum in each chain is from 2 to 20; and (b) a borate ester of the formula:

where R, and R, are independently selected from the group consisting of hydrogen or methyl; R, and R are each an independently selected alkyl group having from one to four carbon atoms; R, is the organic residue exclusive of reactive hydroxyl groups of a polyol, p is an integer of from 2 to 6 inclusive and n and m are positive integers independently selected in each chain and whose sum in each chain is from 2 to 20.

I. i i i 1 mgr UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 635 825 Dated January 97 Inventor) Arthur w. Sawyer and David A. CseJka It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

001. 4, line 8, that portion of the formula reading "(.OCH CHR2)O should read (001120111291 0 col ll, Example X, that portion of the formula reading CH3(OCH2CH2)3O CH3(OCH2CH2)3O B should read Col. 11, Example X, that portion of the formula reading O(CH2CH2O)3CH3 O(CH2CH2O)3CH3 B\ should read B\ O(CH2CH2O)3CH3 O(CH CH O) CH Col. ll, Example X, line 20, "2,128 cps" should read --2l28 cs-- Col. 11, Example XI, line 73 1,656 o e" should read 1656 05-- Col. 12, Erie. XII, and XIII that portion of the formula reading CH2)3O o(cH2cH2 CH2)3O o(cH2c B O -B I should read B-O B CH2)3O o(c1-12cH2 CH2)3O O(CH2C J see attached J L. sheet+ z U. S. Patent No. 3,635,825 Issued January 18, 1972 Sawyer et a1 001. 4, EX. XVIII, that ortion ofthe formula reading CH2)3O CH2) O B should read B 0112030 CH2)30 Co1.l4, EX. XVIII, that portion of the formula reading 0(CH ,o(cH2 B should read 'B 0(0112 O(CH2 Col. 3.2, EX. XIV, line 72, 3,029 ops" should read "5029 cs-- C018. 15, 16, and 17, Examples XX; XXIII; XXIV; XXV; XXVI; that portion of the formula reading should read CH2)3O 01 1930 Cole. 15, 16 and 17, Examples XX; XXIII; XXIV; )QCV; XXVI; that portion of the formula reading C(CHZ '1 /O(CH2 B should read 13- 0(CH2 0(CH Col. 18, line 12, "to" should read -'-of--.

Signed and sealed this 6th day of February 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting- Officer Commissioner of Patents 

2. The hydraulic fluid compositiOn of claim 1 wherein said composition additionally includes from about 0.5 to about 6.0 percent by weight based on the total weight of the fluid to an inhibitor for pH and corrosion control.
 3. The hydraulic fluid composition of claim 2 wherein said composition additionally includes from about 0.001 to about 1.0 percent by weight of an antioxidant.
 4. The hydraulic fluid composition of claim 3 wherein the said base or lubricant is:
 5. The hydraulic fluid of claim 3 wherein the said base or lubricant is:
 6. The hydraulic fluid of claim 3 wherein the said base or lubricant is:
 7. The hydraulic fluid of claim 3 wherein the said base or lubricant is:
 8. The hydraulic fluid of claim 3 wherein the same base of lubricant is:
 9. The hydraulic fluid composition of claim 3 wherein the said polyoxyalkylene glycol is a polyethylene glycol having a molecular weight of
 300. 10. The hydraulic fluid composition of claim 3 wherein the said diluent is triethylene glycol monomethyl ether.
 11. The hydraulic fluid composition of claim 3 wherein the said antioxidant is a mixture of sodium nitrite and phenothiazine.
 12. The hydraulic fluid composition of claim 3 wherein the said inhibitor is diethanolamine.
 13. The hydraulic fluid of claim 1 wherein the base or lubricant portion is from about 44 to about 92 percent by weight based on the total weight of the fluid composition.
 14. In the operation of a fluid pressure operating device which uses hydraulic pressure transmission fluid, the improvement comprising using as the base component in said hydraulic pressure transmission fluid at least one borate ester selected from the group consisting of (a) a borate ester of the formula: wherein R1 and R2 are independently selected from the group consisting of hydrogen and methyl; R3, R4, R5 and R6 are each an independently selected alkyl group having from one to four carbon atoms and n and m are positive integers independently selected in each chain and whose sum in each chain is from 2 to 20; and (b) a borate ester of the formula: where R1 and R2 are independently selected from the group consisting of hydrogen or methyl; R7 and R8 are each an independently selected alkyl group having from one to four carbon atoms; R9 is the organic residue exclusive of reactive hydroxyl groups of a polyol, p is an integer of from 2 to 6 inclusive and n and m are positive integers independently selected in each chain and whose sum in each chain is from 2 to
 20. 